1. Field of the Invention
The present invention relates to image sensing apparatuses such as digital still cameras and digital video cameras.
2. Description of Related Art
Recent years have seen eager development of technologies for suppressing image blur ascribable to camera shake or subject movement. Some of such technologies achieve blur correction optically, but optical blur correction requires a sensor for detecting shake and a mechanism for optically compensating for it. Incorporation of such a sensor and a mechanism, however, is disadvantageous in terms of cost and compactness. This has led to proposal of various technologies for correcting blur through image processing after shooting.
For example, according to one conventional method, a first image having a high resolution but containing much noise is shot by exposure lasting for a short exposure time and in addition a second image having a low resolution but containing little noise is shot by exposure lasting for a long exposure time. Then, based on the image data of the first and second images, the displacement between the two images is detected; their positions are then so adjusted as to cancel the displacement, and thereafter the first and second images are synthesized to generate a corrected image.
Such image synthesis processing involving position adjustment between a first and a second image is intended to generate an image containing little blur and little noise, but the position adjustment cannot always be executed accurately. Failure of position adjustment may result in, in a corrected image, a subject appearing doubly or, in synthesis processing, an abnormally high synthesis ratio of one image, producing much blur or noise in a corrected image.